The Symbiote appears as the main antagonist in Spider-Man 3. As in the comics, the symbiote attaches itself to Spider-Man first, but instead of giving him his classic black costume (like in the comics), it gives his red & blue costume a new, black color, with his usual webbing pattern on it and a slightly different spider symbol. After Spider-Man discovers the symbiote's true nature and realizes that it seeks to bond with him completely and take over his life, he separates himself from the symbiote by tearing off his black costume in an active church bell-tower. The symbiote then moves to Eddie Brock, Jr., and the merger becomes Venom. The symbiote is revealed to have crashed down to Earth via a meteorite and clung onto the back of Peter's moped at the very start of the film, before their bonding.

Venom concept art

Concept art of the Venom suit, which possesses a webbing motif, unlike the comics, in order to show the symbiote's control and represent the character as a twisted foil to Spider-Man.

Venom appears similar to the comic book version, but with a disorganized web-pattern on his costume. He is also not as muscular as his comic counterpart. Instead, Venom is slightly above medium build as compared to the moderate build of Spider-Man. He fires webbing from the top of his hands, as in the comics, but his webbing is black in color and resembles barbed wire. The Symbiote is also seen crawling across the ground, rather than flowing like liquid as its comic counterpart does. In the Spider-Man 3 novelization by Peter David, the symbiote forms into a large and host less Venom-like creature that grows from Eddie's remains and grows around the construction site pulling itself upwards. Here it attempts to rebond itself to Spider-Man. In the film, Dr. Curtis Connors analyzes a small sample of the symbiote at Peter's request. While he has no idea precisely what it is, he notes that it is similar to a symbiote and upon further testing, later reveals to Peter that the substance amplifies the darker qualities of its host (specifically aggression).